That does help! Thanks Michael :)
On Wed, Jan 10, 2018 at 9:10 PM, Michael Dickens <michael.dick...@ettus.com>
wrote:
> Hi Dave - The tagged stream -> PDU block will generate exactly 1 PDU per
> call to work. In your example, it is possible that all 3 of the PDUs will
> end up being in the stream, but, because of the way "tagged_stream_block"
> works, work() will be called with "ninput_items[0]" being just the value
> entered for the tag representing any given PDU length, no more or less.
>
> This stated, it is possible to end up with multiple same-named tag offset
> values in the stream on the same item; I've seen this recently. There are
> also sometimes other tags within range on the stream. All of the tags that
> aren't removed as the provided length key will be added to the PDU as
> meta-data. This might be the source of your "multiple offset values"
> comment.
>
> Hope this helps! - MLD
>
> On Wed, Jan 10, 2018, at 8:32 PM, Dave NotTelling wrote:
>
> Thanks for the response! Apologies for the unclear question. Here's
> another shot:
>
> Can one call to the work function yield multiple offsets from the
> `get_tags_in_range(0, nitems_read(0), nitems_read(0) + noutput_items)`
> call? With multiple offsets then that means there are multiple sets of
> PDUs (assuming that the stream was created from pdu_to_tagged_stream).
> Let's say for fun that there are 3 PDUs like the following (CAR, CDR):
>
>
> - ( {'pdu_len': 10, 'offset': 0, 'frame' : 1}, (0x00 0x00 0x00 0x00
> 0x00 0x00 0x00 0x00 0x00 0x00) )
> - ( {'pdu_len': 10, 'offset': 10, 'frame' : 2}, (0x00 0x00 0x00 0x00
> 0x00 0x00 0x00 0x00 0x00 0x00) )
> - ( {'pdu_len': 10, 'offset': 11, 'frame' : 3}, (0x00 0x00 0x00 0x00
> 0x00 0x00 0x00 0x00 0x00 0x00) )
>
> What I'm curious about is whether or not a single call to work() will end
> up with tags for more than one of the PDUs above. For instance, if the
> buffer for the block is large enough, would 20 samples get lumped in to a
> single call to work() resulting in say offset 0 and offset 10 both showing
> up in 'get_tags_in_range(0, nitems_read(0), nitems_read(0) +
> noutput_items)'? This of course assumes that pdu_to_tagged_stream and
> tagged_stream_to_pdu both are set to use 'pdu_len' as the length tag.
>
> I seem to remember having that very issue once. I got multiple
> offset values in a work() function in the past. Pretty sure I did at least
> O.o Really, just curious if there is a guarantee somewhere deeper in the
> block code that ensures that can't happen.
>
> As I write this I realize that this is a pretty easy thing to test
> out. If it's still unclear, then I'll just do that and post results :)
>
>
>
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